The field of art to which this invention pertains is the preparation and treating of a fluid catalytic cracking unit (FCC) feed and the production of an ultra low sulfur diesel stream with high quality and high cetane index from a hydrocarbonaceous feedstock of straight run and/or cracked stock origin. Hydrotreating processes have been used by petroleum refiners to produce more valuable hydrocarbonaceous streams such as naphtha, gasoline, kerosene and diesel, for example, having lower concentrations of sulfur and nitrogen. Feedstocks most often subjected to hydrotreating are normally liquid hydrocarbonaceous streams such as naphtha, kerosene, diesel, gas oil, vacuum gas oil (VGO), and reduced crude, for example. Traditionally, the hydrotreating severity is selected to produce an improvement sufficient to produce a marketable product. Over the years, it has been recognized that due to environmental concerns and newly enacted rules and regulations, saleable products must meet lower and lower limits on contaminants such as sulfur and nitrogen. Recently new regulations are being proposed in the United States and Europe which basically require the complete removal of sulfur from liquid hydrocarbons which are used as transportation fuels such as gasoline and diesel.
Hydrotreating is generally accomplished by contacting the hydrocarbonaceous feedstock in a hydrotreating reaction vessel or zone with a suitable hydrotreating catalyst under conditions of elevated temperature and pressure in the presence of hydrogen so as to yield a product containing desired maximum limits of sulfur. The operating conditions and the hydrotreating catalysts within the hydrotreating reactor influence the quality of the hydrotreated products.
Although a wide variety of process flow schemes, operating conditions and catalysts have been used in commercial hydrotreating activities, there is always a demand for new hydrotreating methods which provide lower costs and required product quality and specifications. With the mandated low sulfur transportation fuels, the process of the present invention greatly improves the economic benefits of simultaneously producing hydrotreated cracking feedstocks and low sulfur diesel stocks in one unit. The hydrotreated cracking feedstock will allow the production of low sulfur gasoline to be produced from a downstream FCC unit.